How To Backwash a Pool Sand Filter


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After a period of time, the contaminates in a sand filter start to clog the sand to the point where water flow is significantly diminished and the pressure gauge rises 8 to 10 psi above normal operation readings. To clean out the contaminates, you have to backwash the sand. This guide shows you the steps in backwashing a filter.

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Click Here to View Replacement Parts for Sand Filters 


Step by Step


Step 1

Turn off power to your pool pump at the circuit breaker. To prevent damage to the valve, or any other pool equipment always turn off the pump before moving the multiport valve’s handle

Step 2

Depress the valve’s handle and turn it until the selector notch points to BACKWASH, then release the handle.

Tip for preventative maintenance: Always turn your valve’s handle the same direction when changing settings; either always right or left. Do not turn opposite direction even if the other way is a shortcut to your desired setting. This reduces chances of uniting the spider gasket and undue wear and tear.

Also, make sure the handle is fully depressed when turning the selector handle.

Step 3

Make sure Waste hose is securely connected to the valve, and free of kinks to allow for free flow to your desired drainage point.

Please Click Here to View the Backwash Hose

Please Click Here to View Hose Clamps

Step 4

Turn on the pool pump breaker, then turn on the pool pump. Let the pump run for about two minutes or until the water in the sight glass is free of silt. 

Note: If you’re planning a longer than normal backwash and rinse due to an excessively dirty filter, set you suction diverter to only pull water from your main drain. Making this change will prevent your pump from losing prime or running dry if the pool’s water level drops below the skimmer.

Step 5

Turn off the pump again

Step 6

Set the valve to Rinse. Depress the valve selector handle, then turn it to the Rinse setting. After a backwash, sand and debris becomes unsettled settle in the filter’s internal plumbing. The rinse setting returns to the normal path through the filter, flushing debris to waste.

Step 7

Turn the pump on, let it run for about a minute or until the sight glass is clear of silt and sand.

Step 8

Turn off power to pump to set the valve selector handle to its normal Filter setting.

Step 9

Turn on the pump to resume a normal filtering schedule. Check your pressure gauge to ensure the system’s pressure has returned to your pool’s normal “clean” PSI range.

Please Click Here to View Pressure Gauges.

If you experience issues after backwashing, here is a list of helpful how-to guides for troubleshooting:

How To Determine Why a Pool Pump Won't PrimeSand in Your Pool?

How to Reduce High Pressure in Your Pool System

How to Correct Low Water Pressure in Your Pool System


(81 to 120 of 310)

 Posted: 6/25/2017 

I have a 1 year old Hayward sand filter. I have to backwash & rinse every 2 days or so only because I don't get the flow in the pool like I should. the pressure only fluctuates 2 psi. it starts back like a champ but 2 days later the water is almost calm.

 Posted: 6/24/2017 

First time pool owner:
We have had record amount of rain fall lately. The water level is quit high. Can I use the backwash feature to drain the water?


InyoPools Product Specialist  Posted: 6/22/2017 

Peanut - It sounds like you have a significant break in one of the filter's laterals, the hub that the laterals go into, or the standpipe coming up from the hub to the top od the filter. You will have to take the sand out of your filter to see this. Seer our guide on "How To Change Sand In a Sand Filter".

 Posted: 6/20/2017 

I vacuumed my pool because there was a lot of dirt (sand) and them back washed it and turned it back to filter, I got up today and the whole bottom of my pool is full of sand. what did I do wrong?

InyoPools Product Specialist  Posted: 6/11/2017 

Patti - You may have a damaged spider gasket in the MPV. See our guide on "How to Replace a Spider Gasket on a Multiport Valve".

 Posted: 6/9/2017 

After backwashing and rinse, put it back to filter turned it back on and water is still coming out of there

InyoPools Product Specialist  Posted: 6/1/2017 

Mel - I wouldn't worry about a yellowish sight glass. Water is only seen in the sight glass when it is flowing out of the waste line during backwash and rinse. If the water in the waste line is clear, your site glass is ok.

 Posted: 5/29/2017 

After backwashing and rinsing, my sight glass is yellowish with a little sand in the bottom. (was clear until about 3 days ago. How do I correct this problem? The water coming out of the backflush is clean and clear as is the rinse water

InyoPools Product Specialist  Posted: 5/25/2017 

Suzie - Here's an example of how to hook up a suction cleaner through your swimmer - "How To Set Operate the Zodiac X7 Cleaner Through a Skimmer". And, we don"t sell refurbished equipment. Sometimes we do have scratched or dented sales but infrequently. Look for "Clearance Items" in the class of products you may be interested in.

 Posted: 5/24/2017 

can you tell me how to hook up my sand filter pump so that I can use it as a pool vacuume too. I have the hose hooked to the intake so that I can constantly sweep the floor with the vacuum upon entry is this correct. Do you all sell refurbished sand filter pumps?

InyoPools Product Specialist  Posted: 5/6/2017 

Kate - You don't have to change anything on your system. Just turn off your pump before you change your multiport valve to "Backwash". Then turn it back on. Also, we recommend turning the handle on your multiport valve in one direction each time your change the mode.

 Posted: 5/6/2017 

Very new to this, do I turn off the refueller' and skinners when I am back washing.

InyoPools Product Specialist  Posted: 5/1/2017 

George - It sounds like your spider gasket in your multiport valve is damaged. See our guide on "How to Replace a Spider Gasket on a Multiport Valve". To minimize damage in the future remember to shut off the pump before changing filter modes and only turn the handle in one direction to change modes.

 Posted: 4/29/2017 

Why do I have water trickling through my back-wash hose when pump is running on filter is the sand dirty in the filter.

InyoPools Product Specialist  Posted: 3/31/2017 

Charlotte - Not sure I understand your question. The only way you could have drained your pool to 8" was to close off all the incoming ports (skimmer and suction line) that went above the water line. Otherwise, your pump would have sucked in air and lost prime. All your water to the pump would then be coming from the main drain below the water surface - and going out the waste line. Also when draining your pool, you would use the "Waste". There is no reason to drain the pool water though the filter in the "Backwash" setting.

 Posted: 3/29/2017 

I have just drained my pool. It won't suck the last 8" of water out. I currently have it set to waste. Can I switch it to backwash from the bottom drain?

InyoPools Product Specialist  Posted: 3/28/2017 

nolan6324 - Here is a link to a blog we just published, "Reducing High Pressure In Your Pool System". It may be able to help you. Check the easy issues first, like a bad pressure gauge or too many diverter valves shut off between the filter and the return jets.

 Posted: 3/26/2017 

Good evening, I just bought an Above ground pool at the end of last summer with a Hayward filter. Closed it down for winter, and now I have turned on and Have backwashed several times, but the pressure is around 50 and in the summer ran around 10. This is a brand new filter and pool. I am not real familiar with pools, what do you think is going on? help please.

InyoPools Product Specialist  Posted: 2/2/2017 

Tim - You can keep the skimmer and self-cleaning system on while your backwash your filter. The backwashing process does not take that long for the other operations to have an effect.

 Posted: 1/31/2017 

Thanks so much for providing a great blog. I just moved into a new place that has a pool. I have a lot to learn. Just checking, when backwashing, does it make a difference if there is a self cleaning system that uses jets to push everything to the middle of the pool which then sucks it all up. Should I simply keep the skimmer and self cleaning system off when backwashing?

InyoPools Product Specialist  Posted: 12/5/2016 

Ruan - You may have a damaged spider gasket in your multiport valve that is allowing water to flow down the wrong paths. See our guide on "How to Replace a Spider Gasket on a Multiport Valve".

 Posted: 12/3/2016 

Hi there if i backwash my swimming pool a few minutes and rinse it and turn to filter a lot of dirty water goes back to swimming pool for about 10 - 20 seconds? im concerned one of the filter fingers may be broken there is sand inbetween the dirt but not much or could the filter have a bit too much sand? before it worked 100% it suddenly started with this problem?

InyoPools Product Specialist  Posted: 11/14/2016 

backwashing - You may be backwashing too frequently so your water doesn't get that dirty or you may have a damaged spider gasket. See our guide on "How to Replace a Spider Gasket on a Multiport Valve".

Anonymous  Posted: 11/11/2016 

When I backwash, there is no dirt going through the sight glass. The water remains clear from the start and I hear an air leak when I'm finished

InyoPools Product Specialist  Posted: 9/13/2016 

valbo - It sounds like you problem is the pump not priming. See our guide on "How To Prime a Pool Pump". Also check to see if your pump's impeller is clogged. See our guide on "How To Clean Out a Pool Pump Impeller".

 Posted: 9/10/2016 

All valves are open and my hose is ready to receive dirty water. I've set to backwash and turned on the pump. No water leaving the filter, pool, anything. Any advise on why and what to do now?

 Posted: 8/10/2016 

My filter pressure runs 14 psi after a good flush. One return jet to above ground 24' pool. I feel good pressure from the jet about three feet into the pool. When this declines significantly to say a foot from the jet, I figure I am overdue for a backflush. The pressure rise is only about 3. Hayward 100 pound sand, 2-horse pump.

InyoPools Product Specialist  Posted: 7/28/2016 

TMK - It sounds like you may have a damaged spider gasket in your multiport valve. See our guide on "How to Replace a Spider Gasket on a Multiport Valve". To prevent damage to the spider gasket, make sure the pump is turned off before changing MPV settings.

 Posted: 7/26/2016 

When I backwash, and this just started two back washes ago, dirty water also gets sent back into the pool through the jets?!? Anybody know what is wrong?

InyoPools Product Specialist  Posted: 7/19/2016 

Judi WV - No, there is no advantage to letting your sand filter sit before backwashing and rinsing. The debris is embedded in the sand. Backwashing lifts the sand up into the top of the tank to separate it and loosen up the debris to be purged out the waste line. Rinsing pushes the sand back down to repack it and remove any loose debris left in backwashing.

 Posted: 7/17/2016 

I am new to using a sand filter. Had DE filter in the past. My question is, is it best to let the filter sit not running for any length of time before backwashing and rinsing in order for debris to settle? It is a Hayward sand filer.

InyoPools Product Specialist  Posted: 7/12/2016 

kathy - The sight glass in on the Waste port and only shows flow when the water is going out the Waste post. Check your pump impeller to make sure it is not clogged and restricting good flow. Check your chemical balance and in particular the pH valve. Get your pH value down to 7.4. High pH can contribute to a cloudy pool. If none of these suggestions work, backwash your filter, shock your pool, and run your pump continuously until the pool is clear. Backwash your pool 2 times a day while the pool is clearing.

InyoPools Product Specialist  Posted: 7/11/2016 

Jgibson - If you haven't replaced the sand in your filter for a while, you might try that. Or sometimes the pressure gauge itself goes bad and needs to be replaced.

 Posted: 7/10/2016 

my pool has been cloudy all season. Just changed 150 lbs of sand in my Hayward Sand filter. Still cloudy. 2 days later, I just noticed that the water is not moving freely around like it normally does in the sight glass while the filter is running. The water is just sitting, stagnant in the sight glass. Any idea why the water in the sight glass is not moving around like it usually does while the filter is running?

InyoPools Product Specialist  Posted: 7/8/2016 

Leaking backwash - It sounds like the spider gasket in your Multiport Valve may be damaged and is letting water leak into the Waste port. See our guide on "How to Replace a Spider Gasket on a Multiport Valve" to locate and possibly replace this gasket.

 Posted: 7/8/2016 

I have a 15x48 round above ground pool. The pressure gauge on my Proline 94440 Sand Filter hovers around 29 PSI. I have back washed it a few times since opening the pool two weeks ago. However, the PSI has not dropped. Do I need to replace anything?

Anonymous  Posted: 7/5/2016 

After back washing I placed the valve back in filter mode as always. This time the system continued to slowly fill the hose with water as if I were still back washing. The system continues to remove water from the pool. What should I do to stop this from happening. I am refilling the pool with water. Help

InyoPools Product Specialist  Posted: 7/2/2016 

ksmart - In BACKWASH mode the water should come out the Waste port. See our guide on "How a Multiport Valve Operates".

 Posted: 7/1/2016 

ok, where is the water supposed to come out when I BACKWASH my sand filter?

InyoPools Product Specialist  Posted: 7/1/2016 

Sanmann7 - Make sure your pool chemicals are balanced. Have your pool store check your phosphates level. That can cause cloudiness. Also, backwash and rinse the sand 2-3 more times to clean out the filter.